The present invention relates to an engine power controlling apparatus and method that control torque generated by an engine.
For example, Japanese Laid-Open Patent Publication No. 10-325348 discloses engine torque demand control, in which a target torque for idling an engine is determined based on the difference between a target engine speed and an actual engine speed, and the engine power is controlled such that the target torque is obtained.
Instead of PID control or PI control based on the engine speed as described above, Japanese Laid-Open Patent Publication No 5-248291 discloses a type of modern control in which an engine is modeled to derive an evaluation function, and the engine is controlled such that the value of the evaluation function is minimized.
The technique disclosed in the first publication includes PID control or PI control, in which engine torque is subjected to feedback control based on phenomena that actually occur in the engine speed according to adjustment of a controlled subject such as the opening degree of a throttle valve. Therefore, the adjusted amount of the engine torque does not reflect any physical basis. Therefore, it is difficult to determine the balance between the convergence property and the responsiveness through the feedback gain. Accordingly, the responsiveness to an operation for changing the torque has to be lowered.
In the technique disclosed in the second publication, the responsiveness does not need to be lowered as in the first publication. However, the manner in which the operation is performed cannot be understood intuitively, and it requires a number of steps to correct deviations between the control on the model and the control of the actual engine. Thus, the control of the second publication is not suitable for mass production.